Color photography and cinematography



J. H. REINDORP 2,153,698

CDLOR PHOTOGRAPHY AND CINEMATOGRAPHY April 11, 1939.

Filed Oct. 2l, 1936 5 Sheets-Sheet 2 XPOIED 4 VERY Fig. 3.

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COLOR FHOTQGRAPHY AND cmmmosawax Filed om. 21, 195e s sheets-sheet s Fig. 4.

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uw MM/w yM/MMM? v Patented Apr. 11, 1939 John Hubert Eeindorp. London, England, assignor to Truecol our Film Limited, London, England, a British company Application 11 claim.

The present invention relates to improvements in color photography or cinematography and it is 'particularly concerned with the production of multicolor images suitable for use in the subtractive process. 'I'he invention is applicable both to the production of different color sensations in a plurality of superposed emulsion layers and also to the productionrof different color sensations in different strata of a single emulsion layer. By the processes in accordance with the invention it is possible to obtain two different color sensations either in a single emulsion layer or in two superposed emulsion layers, and it will be understood that such two color records may be combined with a further emulsion layer or further emulsion layers carried, for example, on the opposite side of a single support or on a second support to form a three, four or more color record. Attempts have already been made to obtain different color sensation records in a plurality of superposed emulsion layers, but the methods by which the desired results have been obtained are relatively complicated and difllcult of accomplishment in such a manner as to obtain satisfactorily balanced records in the diiferent layers.

The principal object of the present invention is to provide a process for coloring two super- "posed emulsion layers or two strata of a single emulsion layer in a relatively simple manner and in such a way that satisfactory color balance of the resulting images can be maintained.

' The method of obtaining two diiIerent colored records in either one or two emulsion layers, in accordance with the present invention, includes the step of rendering the upper layer of emulsion in the case of the double-coated lm, or the l upper stratum of a single emulsion layer, incapable of development by certaindeveloping solutions, to permit development of the underlying strata or layer and coloring the layers in any desired manner. Vlfy these means the two layers can be dinerentially processed to different colors in a variety of ways. In order to render the upper layer or stratum undevelopable, a solution containing a. soluble iodide may be employed as a pre-treatment bath in which the material that is to be treated is placed before being developed.

By varying the concentration of the iodide, or

the time of the treatment, varying depths of the emulsion layer or layers can be rendered undevelopable, and the desired concentration or period of time to render an outer layer or stratum undevelopable, can only be determined by trial and error. If lt'ls desired subsequently to develop the upper emulsion layer or stratum, it

october 21, 193s, semina. 106,884 Great Britain Aumt zz, 193s (Cl. SI5-2) is necessary to employ a developer a solventV for silver iodide, and moreover, this solvent must be one which brings the silver of the iodized layer into solution with the silver present as a cation. A suitable developing agent 5 for this purpose is a developer containing ammonia, but it is also possible to employ an alkaline amidol developer, that is to say, one containing a suitable proportion of a carbonate. The development of the inner layer can be performed 10 with a diamine developer, which may, if desired, contain additions to permit color development of the said layer.

Instead of employing a solution containing essentially only a soluble iodide to render the upper 15 layer or stratum undevelopable, it is also possible to enly a solution containing. in addition to a soluble iodide, sulphite and either thiocyanate or thiosulphate. In such case it is not necessary containing to employ a developer containing ammonia or other iodide solvent to perform development in the upper layer, since it is possible to select two developers of normal constitution but having different reduction potentials, that with the lower potential being employed for the development 25 of the lower layer, while that having a higher potential is capable of performing development in the upper layer. Where employing a solution containing iodide, sulphite and thiocyanate or so thiosulphate, the proportions of the different components and the time of treatment, and particularly the proportion of the iodide, can only be determined by trial and error in order toensure the treatment of a desired depth of the emulsion in such manner as to render such depth undevelopable.

Reference has been made above to the deve1cp. ment of either the upper or the under layer or stratum, but it should be understood that this development is not necessarily the rst development, namely, that serving to develop latent images in an exposed layer or layers, but the development referred to may also include a second development of a silver salt image, produced by 45 bleaching or otherwise converting a developed silver image into a silver salt image.

The methods of development of upper or under layers or strata, in accordance with the invention, may be applied to the well known process of color development, wherein a dyestui image is deposited contemporaneously with a developed silver image. The present invention also includes the development of upper or under layers or strata to silver and subsequent conversion of the diil'erent diagrams blue-red (magenta) silver image into a coloror dye-toned image by methods well known in the art.

Various methods oi' carrying the invention into eiiect are shown diagrammatically, and by way of example on the accompanying drawings i'n which:-

Fig. 1 (A to G) illustrates the various stages in the processing of a double coated 111m. the composing this ligure being enlarged sectional views, showingfa support and two emulsions coated thereon.

Fig. 2 (A to J) illustrates another method oi' carrying the invention into eiiect, similar to Fig. 1. Y

Fig. 3 (A to G) illustrates a still further method similar to Fig. 1.

Fig. *i (A to G) illustrates two modiiications of the method according to Fig. 3, and Fig. 5 (A to D) illustrates a method oi obtaining a three-color record, wherein two oi the colors are recorded in diil'erent strata of one emulsion, and a third color is recorded in another emulsion layer on the other side of a support.

Example Fig. 1 illustrates the various stages of processling a double coated mm embodying e eeuuioid Fig. 1A is a diagrammatic view, illustrating the ilm after exposure. This nlm is then immersed in the following iodizing ba Potassium iodide grams-- Sodium thiosulphate do Sodium sulphite d,o Water q. s c c..- 1, 000

As a result oi this treatment (Fig. 1B), the upper layer of the nlm is rendered undeveiopable by the developing solution used a latent image in the lower layer. For this purpose the following developer can beV used:-

Diethylparaphenylenediamine hydro- To this solution is added as color "former for p-nitrobenzyl cyanide -gram-.. 0.5 Methyl alcohol c. c-- 50 tively high sulphite concentration, for instance,

a developer having the following composition:-

Metol grams 5. 0 Sodium sulphite do..- 'I5 Sodium carbonate do Potassium bromide do... 0.5 Water q. s `..-c. c 1,000

Potassium ierricyanide ..-grams 20 Ammonia. 28% -c. cs-- 20 Water q. s -do .1,000

which, for purposes of controlling its rate of diffusion is loaded with a suitable quantity of alcohol and glycerine. The action of this bath, when bleaching of the top layer is complete, is stopped immediately by immersion in neutral sulphite solution.

The silver ferrocyanide image so obtained in the upper layer is now redeveloped (Fig. 1F) with a green-red (yellow) color-developing solution, containing, for example, the sodium salt of 1:2:6: aminonapthol sulphonlc acid as the developer, and a napthol as the color former. For example:- (A) Sodium salt oi 1:2:6: aminonapthol sulphonic acid grams-.. 25 Sodium sulphite (crystallized) `cion.. 50 Water q. s c. es-- l, 000 (B) Potassium carbonate (anhydrous) grams-.. 75 Water q. s c. cs-- 1,000

Equal volumes oi' A and Bare mixed, and to every 100 c. c. are added 10 c. c. oi:-

a Napthol grams-- 2.5 Methyl alcohol ..c. cs-- 100 'I'he silver remaining in the two layers is iinally removed by means of a suitable reagent such as Farmers reducer (Fig. 1G).

It will be understood that any additional silver developed in the lower layer during the initial development in the upper layer has no eect on the iinal result since this silver would not be conto silver ferrocyanide during the controlled bleaching operation, and consequently would 'not be capable of re-development by the yellow color-forming developer, and moreover, would be removed in the iinal operation.

In accordance with another method of carrying the invention into effect, shown diagrammatically in Fig. 2, both layers could be initially developed to silver simultaneously (Fig. 2B), for example, in one of the well known metol-hydroquinone fine grain developers. The two layers are then ilxed and washed, and the silver images converted into silver salt and particularly silver bromide, images (Fig. 2C) by treatment in a suitable bleaching bath. The layers are then treated in an iodizing bath (Fig. 2D) containing, in addition to iodide, sulphite and either thiocyanate or thiosulphate, so that the action extends throughout the upper may be obtained as in casacca ing in the lower layer is then developed in a magenta color-forming solution such asthat re-. ferred to inthe previous example (Fig. 2E), no further development then occurring in the upper layer. The silver developed, as a result of this magenta color-forming development, is then removed (Fig. 2F) by treating the film in a solution which behaves as a silver solvent, but which does not affect the image in the upper layer, e. g.,

- a` mixture of potassiumferricyanide and ammonium thiocyanate; the former serves tor oxidize the silver, and the latter acts as a solvent. This silver solvent is well known in the art as Haddons reducer. There is now a dye image only in the lower layer, The upper layer is now re-developed to a silver image (Fig. 2G) for example by means of a metol developer having a relatively high sulphite concentration, e. g., that given in the foregoing example. The silver image produced is then bleached (Fig. 2H) to silver ferrocyanide in a suitable bleachingbath, and is redeveloped in a yellow color-forming developer as suggested above (Fig. 21,). Finally, the silver in the upper layer is removed by suitable silver solvent so as to leave pure dye images in the two layers (Fig. 2J).

In a third method of carrying the invention into effect, shown in Fig. 3, the upper layer may first be developed in a developing solution loaded with, for example, glycerine and alcohol to control the rate of penetration of this developing agent (Fig. 3B). This layer is now subjected to an iodizing treatment (Fig. 3C) in the solution given above to render this layer incapable of further develop-ment, and the lower layer is then developed with a magenta color-forming developer such as that specified above (Fig. 3D), after which the two `layers are xed and washed, and the silver image' in the top layer converted to silver ferrocyanide, in a loaded bleaching bath, i. e., one containing a suitable proportion of glycerine and alcohol, so that the silver of the lower image is not affected (Fig. 3E); This upper layer is then re-developed with a yelow color-forming developer such as that mentioned above (Fig. 3F). Finally, the silver in both layers is removed, for example by means of Farmers reducer (Fig. 3G).

Fig. 4 illustrates two modifications of the methcd according to Fig. 3, starting in each oase from the stage illustrated at D, Fig. 3. After this stage the two layers are fixed and washed as shown at A, Fig. 4, and then in accordance with the modification in diagrams B, C and D, the upper layer is first treated in a solution containing iodine and potassium iodide in suitable concentration so as to convert the silver image in the upper layer into a silver iodide image. A suitable bleach bath for this purpose is a solution containing 6% potassium iodide, 0.4% iodine. This operation is performed under time controlled conditionsto ensure the treatment of the image in the upper layer without substantially affecting the image in the lower layer. The penetration of the solution maybe arrested bythe insertion of the material in a solution of sodium sulphite. There is now a silver iodide image in the upper layer which can act as a mordant for a suitable dyestuff, and the next step in accordance with the present modification consists in the insertion of the film in a solution of a basic dyestufl. of suitable color, which is mordanted in the upper layer under the control of the silver iodide image therein. This step is illustrated at C. The dye mordanted in the upper layer may now be fixed therein by means of silico-tungstic acid or phospho-tungstic acid for example. Finally, the silver in the lower layer, and the silver iodide in the upper layer are removed, for example, by means of Farmers reducer. i

In the second modification illustrated in diagrams E, F and G, the coloring of the upper layer is produced as described in British Patent' Specification 377,706 by applying a colloid layer containing pigment or a dye lake of suitable color to the upperlayer in a warm state. The material is then inserted in a bleaching and hardening bath which reacts with the metallic silver in the upper layer, and liberates a hardening agent which 1ocally hardens the applied colloid layer adjacent the silver image in the upper layer. The unhardened parts of the colloid layer are now washed out in warm water, leaving a colored image in contact with the upper layer, which corresponds to the silver image present in said upper layer. Finally, the silver in the two layers is removed by means of a suitable solvent, leaving a pure dyestuff image in the lower layer, and a colored image in the colloid layer applied to the upper emulsion layer. In this modiflcationthe layers need not be xed before the application of the colloid layer.

It will, of course, be appreciated that two co1- or images produced in superposed layers, or in two strata of a single emulsion layer, may be combined with one or more color record images to produce a three or more color record. For example, a photographic material could be employed comprising a base of celluloid or like transparent material, carrying on one side two superposed emulsion layers which couldbe treated by the method specified above to produce different color images therein, while on the other side of the support there might be either a single emulsion layer or two superposed layers. This layer or layers can be coated with a protective varnish layer to prevent the developing solutions reaching that layer or layers during the processing of the two superposed layers on the other side of the support, or alternatively, the layer or layers on the two sides of the support could be differentially processed by fotation methods. Where there are two emulsions on each side of the support, each of the two layers could be subsequently or simultaneously developed by the process described above, or by any other modication of processing technique.

The invention may be applied to the production of three or more color records in various ways; one of which is illustrated in Fig. 5 by way of example. This figure represents the stages in the production of a` three-color record, by printing from a master record of the tri-pack type. copy material is illustrated in Fig. 5A, and comprises a ,support of celluloid or like material l, carrying on one side an orthochromatic emulsion layer, and on the other side a red sensitive emulsion layer, a yellow filter layer being provided on either side of the support l. Printing may be performed onto the said copy material from three partial negatives successively by means of different colored printing lights. From the blue filter negative a latent image may be printed in the upper portion or stratum of the orthochromatic emulsion layer by printing from that side of the support with blue light. From the red filter negative, 'by means of green light, a latent image is printed in the lower stratum of the orthochromatic layer` from the other side of the support i, that is, through the Vred sensitive emulsion layer. Finally, from the green filter negative, by means of The red light, a latent image is printed in the red sensitive layer from the same side of the support. The image produced in the outer stratum of the orthochromatic emulsion layer from the blue sensitive layer, which varnish layer may be removed or rendered permeable by suitable reagents when it is desired to perform the .processing of the red sensitive layer. Alternatively, ythe layers on the two sides of the support icould be diii'erentially processed by flotation methods;

As a result of the printing operatio'n, two latent images are formed in the orthochromatic emulsion layer, which images are to be processed to different colors, and in accordance with the invention, this result is obtained by rst iodizing the said orthochromatic emulsion layer, for example, in the iodizing bath referred to in the first example, after which, as shown in Fig. 5B, a silver image is developed in the lower stratum of the emulsion and theV said image is color-toned to blue-green by methods well known in the photographic art. Subsequently, the upper stratum of this emulsion is developed, for example. in a developer having a high sulphite concentration, and the developed silver image is color-toned green-red by known methods (Fig. 5C). Finally, the latent image is developed in the red-sensitive layer, and this image. is color-toned blue-red (Fig. 5D). At a suitable stage in the operation, the unaffected silver halide or other silver salts are removed, so as to leave pure color images. In processes of the type described in the present specification it is often desirable to remove any silver developed in the lower layer before completing the coloring in the upper layer. When the upper layer exists in the form of a silver iodide image, the removal of the silver in the bottom layer may be performed by treating the solution in a ferricyanide bleach bath, such as that given above, to convert the silver in the lower layer into silver ferrocyanide, Without affecting the silver iodide image in the upper layer. 'Ihe said silver ferrocyanide may later be removed by means of a solution of sodium sulphite. When there is a silver image in the upper layer, this image may be converted into silver iodide and then the silver in the lower layer removed as described. The silver iodide can then be redeveloped to silver, if necessary, in an amidol-c'arbonate developer.

In the foregoing the use of certain reagents, defined by the acid radical thereof, has been proposed and it should be understood that sodium or potassium salts thereof could be utilized according to the usual practice in the photographic art.

1. A method of differentially processing to different colors latent images produced by exposure in different strata of an emulsion, which includes the step of treating the emulsion in a solution containing a soluble iodide of such concentration and for such a time that the outer stratum of the emulsion is rendered developable only by high reduction potential developer treating the emulsion in a low reduction potential developer to develop an image in the lower stratum of the emulsion without affecting the upper stratum, developing an image in the upper stratum at any stage following the exposure and producing colored images in said strata.

2. A method of obtaining two differently colored records at different depths of a photographic silver halide emulsion after exposure to produce latent images in the dierent depths, comprising treating the emulsion in a solution containing a soluble iodide of such concentration and for such a time as to'render part of the depth of the emulsion developable by high reduction potential developers only, developing an image in the rest of the depth of the emulsion with a low reduction potential developer, developing an image in the part of the emulsion layer treatedby the iodide solution with a high reduction potential developer and producing differently colored images in the different depths at any suitable stage.

3. A method of differentially processing latent images contained in different depths of a photographic silver halide emulsion to different colors, comprising converting a portion of the depth of the silver halide into silver iodide, developing the 4rest of the depth of the emulson in a low reduction potential developer which does not develop silver iodide, developing .the said `portion of the depth of the emulsion with a high reduction potential developer which develops silver iodide and producing colored images in the different depths at any suitable stage.

4. A method of producing multi-color photographic records comprising producing latent images of different color aspects at different depths of a photographic emulsion, treating the emulsion in a solution of a soluble iodide of such concentration and for such a time that the latent image at the outer side of the emulsion is rendered developable by high reduction potential developers only, developing the latent image at the inner side of the emulsion by means of a low reduction potential developer, developing the latent image at the outer side of the emulsion with a high reduction potential developer at any stage following the exposure and producing differently colored images in the portions of the'depth of the emulsion which contained the latent images.

5. A method of obtaining differently colored i records in a photographic material embodying two emulsion layers, superimposed on the same side of a support, after exposure to produce latentimages in such layers, which includes the steps of treating the material in a bath containing. a soluble iodide of such concentration as to render the upper layer capable of development by high reduction potential developers only, developing the lower layer, in a low reduction potential developer, treating the layers in a high reduction potential developer to develop an image in the upper layer, and producing color records in the two layers.

6. A method of obtaining diiferently colored records in a photographic material embodying two emulsion layers superimposed-on the same side of a support, after exposureto produce latent images in such layers, which includes the steps of treating the material in a solution containing a soluble iodide, sulphite, and an alkali salt of a thio acid selected from the group consisting of thiocyanate and thiosulphate to render the upper layer developable by high reduction potential developers only, developing an image in the lower layer in a developer having a relatively low reduction potential, developing an image in the upper layer in a solution having a higher reduction potential, and producing colored images in said layers.

`a soluble iodide to render the upper layer o1' emulsion capable of development by a high reduction potential developer only, developing the lower layer in a low reduction potential developer, then performing development in the upper layer with a-high reduction potential developer in the presence of a solvent capable of bringing the silver in the upper layer into solution with the silver present as a cation and producing colored images in said layers.

8. A method according to claim 7, wherein a developer containing ammonia or an alkaline amidol developer is used for the development of the said upper layer.

9. A method of obtaining differently colored records in a photographic material embodying two emulsion layers superimposed on the same side of a support, after exposure to produce latent images in such layers, which consists in treating the material in a solution containing iodide to render the upper layer developable by high reduction potential developers only, developing a color image in the lower layer with a low reduction potential, color-forming developer, developing an image in the upper layer in a high reduction potential developer, converting said latter image into a developable silver-salt image and redeveloping in a color-forming developer.

10. A method of obtaining differently colored records in a photographic material embodying two emulsion layers, superimposed on the same side of a support, after exposure to produce latentimages in such layers, which consists in developing a silver image in the upper layer in a developer loaded to reduce its rate of penetration, treating the material in an iodide solution to render said upper layer incapable of further development by low reduction potential developers, color-developing -an image in the lower layer with a low reduction potential, color-forming developer, converting theimage in the upper layer into silver ferrocyanide and redeveloping said silver ferrocyanide image with a color-forming developer.

11. A method of obtaining differently colored records in a photographic material embodying two emulsion layers superimposed' on the same side of a support, after exposure to produce latent images in s uch layers, which consists in developing a silver image in the upper layerV in a developer loaded to reduce its rate of penetration, treating the material in a solution of a. soluble iodide to render the said upper Alayer incapable of further development by low reduction potential developers, color-developing the image inthe lower layer in a low reduction potential colorforming developer, transforming the image in the upper layer into silver iodide, and dye-toning said latter image.

12. A method of obtaining differently colored records in a photographic material embodying two emulsion layers superimposed on the same side of a support after exposure to produce latent images in such layers, Awhich consists in developing a silver image in the upper layer in a developer loaded to reduce its rate of penetration, treating said image in an iodide solution to render same incapable of further development by low reduction potential developers, color-developing the image in duction potential color-forming developer, applying a colored colloid layer to the upper layer, treating the composite material in a bleach-hardening bath and washing out the unhardened parts of the colloid layer.

13. A method of processing the under layer of a iilm carrying two superimposed emulsion layers to one color, and the upper layer thereof to another color after exposure to producelatent images in such layers, which includes the step of mmersing the layers in an iodizing bath containing, in addition to a soluble iodide, sulphite and an alkali salt of a thio acid selected from a group consisting of thiosulphate and thiocyanate of such concentration and for such a time as to render the upper layer capable of development by high reduction potential developers only, treating the nlm in a low reduction potential color developer to color the under layer -to the desired color, developing the latent image in the upper layer to silver in a high reduction potential developer having arelatively high sulphite concentration and coloring said developed image.

14. A method according to claim 13, which includes bleaching the silver image in the upper layer subsequent to development therein to silver lerrocyanide, and re-developing in a colordeveloping solution.

15. A method of processing a nlm having two superimposed emulsion layers to produce different color records in the two layers after exposure to produce latent images in such layers, comprising developing both layers simultaneously to silver, bleaching the said images to silver salt images, treating the lm in an iodizing bath containing a soluble iodide, sulphite and an alkali salt of a thio acid selected from a group consisting of thiosulphate and thiocyanate of 4such concentration and for such a time as to render the upper layer potential developers only, color-developing the silver salt image in the lower layer to one color with a low reduction potential color-forming developer, removing the silver developed in said lower layer, re-developing the silver salt image in the upper layer to silver in a high reduction potential developer, converting said silver image to silver ferrocyanide, and second color-forming solution.

16. A method of processing a iilm having two superimposed emulsion layers to produce different colors in the two layers thereof after exposure to produce latent images in such layers, comprising developing the latent image in the upper layer with a loaded developing solution, treating the layers in an iodizing bath containlng iodide, sulphite, and an alkali salt of a thioacid selected from a group consisting of thiosulphate and thiocyanate oi such concentration and for such a time as to render said upper layer developable by high reduction potential developers only, performing development in the lower layer with a low reduction potential, color-forml ing developer, fixing and washing the two layers,

converting the silver image in the upper layer re-developing with a` the lower lay'er with a low redevelopable by high reduction into silver ferrocyanide in a loaded bleaching bath, and re-developing the said upper layer with a second color-forming solution.

17. A method of obtaining three-color records in two emulsion layers positioned one on each side of a support which consists in recording in one of said layers, at different depths thereof, two color sensations, by printing from the two sides of the film, recording the third color in the other emulsion layer. processing the two a low reduction potential developer, coloring the latent images in the first layer to diiierent c'ol- `developed image by toning processes, developing ors by irst treating nrst said layer in an iodizthe previously undeveloped portion of said ilrst ing bath containing iodide, sulphi and an alemulsion layer in a developer having a. high '5 kali salt of a thio-acid selected from a group reduction potential, coloring the silver' image 5 consisting of thiosulphate and thiocyanate of produced therein by toning processes and desuch concentration and for such a time as to veloping and coloring the latent image in the render said rst layer developable by a high resecond emulsion layer by any suitable process. ductionv potential developer only, and then per- 10 forming development of the under-lying layer in c JOHN HUBERT 10 

